This invention relates to lighting systems and more particularly to down lighting systems including down lighting emergency lights for elevator cabs and other spaces requiring high efficiency main lighting as well as integrated emergency lighting operative on failure of a main lighting power supply.
Lighting systems for various overhead ceiling systems require that light units be connected to a power supply through various wiring networks and connection arrangements.
It is known to provide standard 110 volt residential or commercial fixtures in overhead ceilings. In some cases the bulbs are 12 volt bulbs energized from a 110 volt system via individual step down transformers connected to power the 12 volt bulbs.
It is also known to provide a plurality of 10 volt bulbs connected to a 110 volt wiring system. The bulbs are mounted either above a egg-crate type grill covering or are hidden by a cover which will diffuse light from the bulbs. In some cases these systems are lighted by means of fluorescent tube lighting.
In cases where 12 volt bulbs are used, a large numbers of fixtures and bulbs are needed to provide enough candle power to illuminate the space below the ceiling system.
Existing down lighting systems use low light output bulbs which have short life or are operated at lower than design voltage to extend the bulb life, but all of which requires a large number of fixtures and elaborate wiring systems for connecting the fixtures to a power source.
In the case of elevator down lighting systems, it is desirable to provide as much direct lighting as possible from the main illuminating lamps both to reduce the number of fixtures required for a given area of ceiling and to reduce the complexity of the wiring system for supplying power to the individual fixtures.
A further problem with known elevator down light systems is that the emergency light source for the elevator is either located in the vicinity of the elevator control panel or is located at an overhead location above the ceiling. Such arrangements require a separate fixture for the emergency lighting. Also, in some cases the emergency light is hidden and it may be necessary to "bend" the light to produce a desired "test point" illumination within the elevator cab. Such emergency lights require more wattage which, in turn, require a larger, more expensive battery and attendant charger.
Another known emergency light system uses two of the down lights normally used for cab illumination. This system is expensive because it requires a large battery pack and charger for each light. Further, one or both bulbs may be burned out when called upon for the emergency mode.